1. Field of the Invention
The present invention relates to a zoom lens and an image pickup device, and particularly to a zoom lens and an image pickup device having a zoom mechanism for a digital video camera, a digital still camera and the like (these cameras will hereinafter be referred to as a digital camera).
2. Description of the Related Art
Digital cameras using an image pickup element such as a CCD (Charge Coupled Device) sensor, a CMOS (Complementary Metal Oxide Semiconductor) sensor or the like have recently spread rapidly and come into common use.
As digital cameras thus become common, there has particularly been an increasing user need for lower prices, smaller size, and higher functionality of digital still cameras integral with lenses. Optical systems in which reduction in thickness is achieved by a so-called collapsible lens formed by a configuration of three groups that are a negative group, a positive group, and a positive group against a background of such a user need are known (see Japanese Patent Laid-Open No. 2005-308953 (hereinafter, referred to as Patent Document 1) and Japanese Patent Laid-Open No. 2008-233161 (hereinafter, referred to as Patent Document 2), for example).
As digital cameras thus become common, there has particularly been an increasing user need for lower prices, smaller size, and higher functionality of digital still cameras integral with lenses. Against a background of such a user need, a zoom lens that is a so-called collapsible lens formed by a configuration of three groups that are a negative group, a positive group, and a positive group and in which a first group and a second group each include only a cemented lens is known (see Patent Document 1 and Japanese Patent Laid-open No. 2007-225864 (hereinafter, referred to as Patent Document 3), for example).
As digital cameras thus become common, there has particularly been increasing user need for lower prices, smaller size, and higher functionality of digital still cameras integral with lenses. Against a background of such a user need, a zoom lens that is a so-called collapsible lens formed by a configuration of three groups that are a negative group, a positive group, and a positive group or a configuration of four groups that are a negative group, a positive group, a positive group, and a negative group and in which a first group and a second group each include only a cemented lens is known (see Patent Document 1 and Japanese Patent Laid-open No. 2006-113404 (hereinafter, referred to as Patent Document 4), for example).